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Thermodynamics of core hydrophobicity and packing in the hyperthermophile proteins Sac7d and Sso7d.
Biochemistry. 2004 Mar 16; 43(10):2840-53.B

Abstract

The influence of core hydrophobicity and packing on the structure and stability of the hyperthermophile proteins Sac7d and Sso7d have been studied by calorimetry, circular dichroism, and NMR. Valine 30 is positioned in Sac7d to allow a cavity-filling Val --> Ile substitution which occurs naturally in the homologous more thermostable Sso7d. The cavity-filling mutation in Sac7d has been characterized and compared to the reciprocal Ile --> Val mutation in Sso7d. A detailed analysis of the stability of the proteins was obtained by globally fitting the variation of DSC parameters and circular dichroism intensities as a function of temperature (0-100 degrees C), salt (0-0.3 M), and pH (0-8). A global analysis over such a range of conditions permitted an unusually precise measure of the thermodynamic parameters, as well as the separation of the thermodynamics of the intrinsic unfolding reaction from the linked effects of protonation and chloride binding associated with acid-induced folding. The results indicate differences in the energetics of unfolding Sac7d and Sso7d that would not be apparent from an analysis of DSC data alone using conventional methods. The sign and magnitude of the changes in DeltaG, DeltaH, TDeltaS, and DeltaC(P) of unfolding resulting from core Ile/Val substitutions in the two proteins were consistent with differences in hydrophobicity of Val and Ile and negligible changes in packing (van der Waals) interactions. The benefit of increased hydrophobicity of the core increased with temperature, with maximal effect around 116 degrees C. Increased hydrophobicity of the core achieved not only an increase in the free energy of unfolding, but also a lateral shift of the temperature of maximal stability to higher temperature.

Authors+Show Affiliations

Laboratory for Structural Biology, Departments of Chemistry and Biological Sciences, Graduate Program in Biotechnology and Bioengineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15005619

Citation

Clark, Andrew T., et al. "Thermodynamics of Core Hydrophobicity and Packing in the Hyperthermophile Proteins Sac7d and Sso7d." Biochemistry, vol. 43, no. 10, 2004, pp. 2840-53.
Clark AT, McCrary BS, Edmondson SP, et al. Thermodynamics of core hydrophobicity and packing in the hyperthermophile proteins Sac7d and Sso7d. Biochemistry. 2004;43(10):2840-53.
Clark, A. T., McCrary, B. S., Edmondson, S. P., & Shriver, J. W. (2004). Thermodynamics of core hydrophobicity and packing in the hyperthermophile proteins Sac7d and Sso7d. Biochemistry, 43(10), 2840-53.
Clark AT, et al. Thermodynamics of Core Hydrophobicity and Packing in the Hyperthermophile Proteins Sac7d and Sso7d. Biochemistry. 2004 Mar 16;43(10):2840-53. PubMed PMID: 15005619.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thermodynamics of core hydrophobicity and packing in the hyperthermophile proteins Sac7d and Sso7d. AU - Clark,Andrew T, AU - McCrary,Bradford S, AU - Edmondson,Stephen P, AU - Shriver,John W, PY - 2004/3/10/pubmed PY - 2004/7/13/medline PY - 2004/3/10/entrez SP - 2840 EP - 53 JF - Biochemistry JO - Biochemistry VL - 43 IS - 10 N2 - The influence of core hydrophobicity and packing on the structure and stability of the hyperthermophile proteins Sac7d and Sso7d have been studied by calorimetry, circular dichroism, and NMR. Valine 30 is positioned in Sac7d to allow a cavity-filling Val --> Ile substitution which occurs naturally in the homologous more thermostable Sso7d. The cavity-filling mutation in Sac7d has been characterized and compared to the reciprocal Ile --> Val mutation in Sso7d. A detailed analysis of the stability of the proteins was obtained by globally fitting the variation of DSC parameters and circular dichroism intensities as a function of temperature (0-100 degrees C), salt (0-0.3 M), and pH (0-8). A global analysis over such a range of conditions permitted an unusually precise measure of the thermodynamic parameters, as well as the separation of the thermodynamics of the intrinsic unfolding reaction from the linked effects of protonation and chloride binding associated with acid-induced folding. The results indicate differences in the energetics of unfolding Sac7d and Sso7d that would not be apparent from an analysis of DSC data alone using conventional methods. The sign and magnitude of the changes in DeltaG, DeltaH, TDeltaS, and DeltaC(P) of unfolding resulting from core Ile/Val substitutions in the two proteins were consistent with differences in hydrophobicity of Val and Ile and negligible changes in packing (van der Waals) interactions. The benefit of increased hydrophobicity of the core increased with temperature, with maximal effect around 116 degrees C. Increased hydrophobicity of the core achieved not only an increase in the free energy of unfolding, but also a lateral shift of the temperature of maximal stability to higher temperature. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/15005619/Thermodynamics_of_core_hydrophobicity_and_packing_in_the_hyperthermophile_proteins_Sac7d_and_Sso7d_ L2 - https://doi.org/10.1021/bi0358263 DB - PRIME DP - Unbound Medicine ER -